Many fluid pressure sensing and measuring devices exist. There has always been a need for an accurate, durable and relatively inexpensive sensor particularly to sense the oil pressure of internal combustion engines such as used in vehicles. Advances in electronics permit this technology to be incorporated in pressure transducers. Small electronic chips are available which sense a pressure differential between two fluids when their pressures are exerted on opposite surfaces of the chip.
A previous patent application relating to such a transducer was filed by a co-worker of the present inventor and assigned to the same employer. Thus the present application is an improvement over this prior application. The improvement concerns sealing means to prevent fluid leakage past the sensor, particularly when it is subjected to a relatively high fluid pressure and is subjected to many heating and cooling cycles. The previous patent application is identified as U.S. Ser. No. 07/114,331 entitled "Electronic Oil Pressure Sensing Device" by P. D. Miller and filed on Oct. 29, 1987.
In addition to the above identified document, a pressure transducer of this general type is disclosed in U.S. Pat. No. 4,513,623 to Kurtz. This transducer shows a sensor package in outline form mounted in a housing recess and sealed thereto by O-rings.
Specific sensor designs comprising spaced flexible plates are disclosed in U.S. Pat. Nos. 4,151,578; 4,158,217; 4,177,496; 4,207,604 and 4,227,419.
U.S. Pat. No. 4,590,400 discloses a transducer with a piezoelectric cylinder pressure transmitter.
U.S Pat. No. 4,320,664 discloses a silicon pressure sensor.
U.S. Pat. Nos. 4,567,395; 4,570,097; 4,620,438 and 4,645,965 disclose transducers for sensing cylinder pressure.
U.S. Pat. Nos. 4,616,114 and 4,633,579 disclose pressure switches disclosing means to seal the active portion relative to the housing.